Summary This proposal requests R13 support for the founding meeting of the Gordon Research Conference (GRC) on Modulation of Neural Circuits and Behavior. Neural circuits control behavior, but these circuits are surprisingly plastic. Thus, neuromodulators can change the gain of circuits and even their function - biasing circuits to act in different modes. Scientists from diverse fields - biology, systems engineering, genetics, ethology, neurology and psychiatry - have increasingly recognized the central importance of neuromodulation for the control of behavior and the exciting links to translational neuroscience research. This inaugural GRC Conference is thus timely and unique because of its emphasis on attracting a multidisciplinary group of participants. The Conference will have a central galvanizing impact on the rapidly developing field of neuromodulation by bringing a new focus to the mechanism of action of dopamine, serotonin and various peptides and growth factors that have essential roles in regulating emotional and cognitive states. Defects in neuromodulatory pathways are increasingly implicated in multiple mental disorders, including depression, addiction and ADHD. Thus, a mechanistic understanding of the functional organization of modulatory circuits, the dynamics of modulatory signaling, the behavioral effects of various modulators, and the role of modulators in neuronal homeostasis, is essential for a fundamental understanding of brain function. Our conference is also unique because it will help bring together scientists from traditionally separate fields that explore the rich diversity of ecologicaly significant behaviors. Thus, the Conference will provide an opportunity for new synergisms between scientists working on modulation of neural circuits and behavior in vertebrate and invertebrate model systems. The meeting is particularly timely because the field of neuromodulation is ripe for transformative new approaches based on recent advances in genetic and optogenetic strategies for examining circuit function. Many of the recent advances in our understanding of neuromodulation have come from scientists in Australia, China, Japan, Korea and other Asian countries. Our conference will alternate between the United States and Hong Kong - ideal locations that will maximize the effectiveness of the Conference in promoting intensive exchange of ideas and techniques between American scientists and those from Europe and Asia. Thus, this GRC will be a driving force for emerging studies of neuromodulation in the United States. We expect that the 2015 GRC on Modulation of Neural Circuits and Behavior will shape future scientific directions and provide critical support for the mission of NIH, particularly NINDS and its sister institutes including NIMH, NIDA and NIA.